Why?  I don't know it just happens.  Usually takes longer.  I would start a rye starter and then slowly convert it to spelt. There is a thread here where it took quite a while.  Might be listed under spelt starters in the search box.

Mini

I did a spelt starter a while back for a 100% spelt loaf that I wanted to make.  Seems to me it went right along the lines of what I would expect to happen if it was a wheat starter.

thank you mini oven and leaddog.  so as not to take a chance, i'll use rye or wheat flour then to do my starter.

My first one was pure Spelt.  I don't want to keep extra starters around so now when I make the 100% Spelt bread I use about 2 or 3 grams of my regular starter and build it up from that.  It works fine and the bread tastes great.

In Crust, Richard Bertinet uses spelt in with the white wheat flour to get his starter going--and then adds 90g of spelt to each loaf after he has moved the mature starter over on to just wheat flour feeding.

I've done this twice now (starting the starter)--both times were great.

But if you want to use the spelt up and are feeling wary, you should definitely add a bit of spelt to your other breads--it gives it a wonderful soft nutty texture.